Short-term Investments (Tables)

6 Months Ended

Jun. 30, 2016

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments Available-for-Sale Securities

Short-term investments consisted of available-for-sale securities as follows (in thousands):

Type of securities as of June 30, 2016	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Corporate debt securities	$	27,909	$	10	$	(1	)	$	27,918
U.S. government-related debt securities	9,909		19		—			9,928
Total available-for-sale securities	$	37,818	$	29	$	(1	)	$	37,846

Type of securities as of December 31, 2015	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Corporate debt securities	$	26,116	$	—	$	(28	)	$	26,088
U.S. government-related debt securities	1,101		—		(1		)	1,100
Total available-for-sale securities	$	27,217	$	—	$	(29	)	$	27,188

Fair Values of Available-for-Sale Securities by Contractual Maturity

The fair values of available-for-sale securities by contractual maturity were as follows (in thousands):

	June 30, 2016		December 31, 2015
Maturing in one year or less	$	34,836	$	27,188
Maturing in one to three years	3,010		—
Total available-for-sale securities	$	37,846	$	27,188

Summary of Investments in Continuous Unrealized Loss Position

The following table summarizes investments that have been in a continuous unrealized loss position as of June 30, 2016 (in thousands):

	Less Than 12 Months				12 Months or Greater					Total
	Fair value		Gross unrealized losses		Fair value		Gross unrealized losses			Fair value		Gross unrealized losses
Corporate debt securities	$	—	$	—	$	1,505	$	(1	)	$	1,505	$	(1	)
U.S. government-related debt securities	—		—		—		—			—		—
Total	$	—	$	—	$	1,505	$	(1	)	$	1,505	$	(1	)